steiger



A. AND W. STEIGER.

GAS FIRED SHAFT KILN FOR BURNING 0R ROASTENG NON-SINTERING SUBSTANCES.

APPLICATION HLE D 050.18. I9I8.

1 ,3 1 7,603. Patented Sept. 30,1919.

2 SHEETS-SHEET I.

A. AND W. STEIGER.

GAS FIRED SHAFT KH N FOR BURNING 0R ROASTING NON-SINTERING SUBSTANCES APPLICATION HLED DEC-18. 1918.

1,317,603. Patented Sept. 30,1919.

2 SHEETSSHEET 2.

w 6 76' r 3 /6 2 1% j n nrrnn s'raans PATENT ogrsrcn.

ARNOLDSTEIGER AND WILHELM STEIGER, OF ZURICH, SWITZERLAND.

GAS-FIRED SHAFT-KILN FOR BURNING OR ROASTING NON-SINTERING SUBSTANCES.

To all whom it may concern:

Be it known that we, ARNOLD STEIGER and IVILHELM STEIGER, citizens of the Republic of Switzerland, residing at Ramistrasse 6, Zurich, Switzerland, have invented certain new and useful Improvements in Gas-Fired Shaft-Kilns for Burning or Roasting Non-Sintering Substances; and we do hereby declare the following to be a clear, full, and exact description of the 1nvention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, Which form a part of this specification.

This invention relates to a gas fired shaft kiln for burning or roasting lime, magnesite, iron ores, other ores and other non sintering materials, which is adapted to be heated by means of producer gas, waste gases from blastfurnaces or other combustible gases. 7

In View of the difference in quality of the material which is burnt, it is necessary to vary the treatment, so as to insure the most satisfactory results. In most cases, success of the operationdepends entirely on the manner in which the charge is caused to descend in the shaft'and on a good and appropriate supply of combustion air.

The object of the present invention. is to provide a gas fired shaft kiln of the kind re.- ferred to, in which the contents are loosened to a high degree in the cooling zone in order to provide an unobstructed passage for the air of combustion which in the furnaces hitherto proposed was forced to rise along the walls of the furnace.

A further object of the present invention is to provide a gas fired shaft kiln in which the material in the cooling zone is sub jected to less friction than in the kilns known hitherto, the formation of dust and the breaking up of the material into small pieces being consequently much reduced. This is of very great importance for the treatment of certain materials, as is the case, for instance, for the treatment of quick lime for the production of carbid.

A still further object of the invention is to provide a shaft kiln sufficiently perfect to overcome without substantial changes in construction, any subsequent occurrences, such. as fluctuations and changes in the ma- Specification of Letters Patent.

Patented Sept; 30, 1919.

Application filed December 18, 1918. Serial No. 267,305.

terial burnt or in the fuel, atmospheric conditions, method of working, etc.

In the gas fired shaft kiln according to this invention, the cross-section of the shaft kiln is suddenly increased in the cooling zone to a considerable amount at least at one point, preferably immediately beneath the combustion zone.

In the shaft kiln according to this invention, the. loosening of the material in the cooling zone is then furthered by a discharging device which per 86, is a known feeding device.

Further, in the shaft kiln according to the invention, the pressure conditions and the quantity of air pumped in by a compressor or blower. and the crosssectional area of passage of means leading thecompressed air into the interior of the kiln, may be modified for the purpose of regulating the pressure and the escaping quantity of air.

In the shaft kiln according to the present invention, the air is also preferably supplied to the contents of the kiln at the maximum pressure through means arranged close to the sole ofthe kiln and at asmaller pressure through conduits arranged nearer to the combustion zone.

Moreover, the conduits aremade so that each may be closed separately by means of throttling elements adjustable from the outside, and near the upper end of the kiln is arranged an air eXhauster.

A construction according to this invention is illustrated by way of example in the accompanying drawings in which:

Figure 1 shows the kiln in longitudinal section; V

Fig. 2 is a cross-section on the line II-II of Fig. 1;

Fig. 3 is a cross-section on the line III-III of Fig. 1 and Fig. 4 is a cross-section on the line IVIV of Fig. 1.

Referring to the drawings, A denotes the shaft of the kiln supported on four columns B. 1 denotes the pre-heating zone. The supply material to this zone is controlled by a charging hopper 4 of known design. 2 denotes the combustion zone and 3 the cooling zone of the kiln. The combustion zone 2 has the smallest cross-section of said three zones, while the cross-section of the cooling zone is suddenly increased'to a considerable amount at two points, namely once immedi- 1 ately beneath the combustion zone 2 and a second time in its lower half. 5 are channels provided inthat part of the wall of kiln which surrounds the upper half of the cooling zone. 7 with the zone 3 by means of a port 6, the cross-sectional area of passage of which can be modified from the outside by means of a throttling member 16-. The channels 5 are connected'to a gas supplyinggenerator 17 by means of conduits 18. 7 is a blower forcing the air of combustion through the kiln. This blower 7 is connected by pipes 7 to small bustle pipes 7 b that supply nozzles Figs. 1 and'2 which are distributed around the-circumference of the kiln. In the conmeans of a sliding member 21 adapted to be adjusted from the outside. 22 (Fig. 2) are I the pressure of the'air passing into the construction illustrated, there are four such nozzles 25. The blower also delivers air through the bustle pipes 7 to valves 22, Fig. 2, that discharge into upward conduits 19 in the interior of the kiln wall having over a por-' '9'closed on the outside by covers 23 are for supplying additional combustion air to the combustion zone .2 when too little air is supplied to said zone through the conduits 18' and 5 and ports 6. 'The quantity of air passing'from each channel 20 into the corresponding conduit 9 can be controlled by adjustable valves which are for controlling duits 19. 10 designates poke-holes. 1

At the upper end of the kiln A is arranged a pipe 8 communicating with the interior of the kiln and connected to an exhauster 24- for exhausting the gases above the stock 'ary frame 12 with an obliquely situated por tion 13 and a movable inclined bottom 14, to.

which a crank mechanism 15 and fro movement.

The speed of the blower'7 and of the ex hauster 2 lca'n be regulated by influencing their driving means.

imparts a to The shaft kiln described hereinbefore works as follows: The firing gases'supplied to the channels 5 pass through the conduits [6 into the upper part of the cooling zone 3 and then into the heatingzone 2, the most intensive combustiontaking place in the lower part ofthis zone 2. The contents sinls- Each channel 5 communicates the cooling zone.

duced. V

The com-pressedv air produced by the blower-7 is supplied at. the highest pressure ing from'the latter into the'cooling zone 3 are loosened in the latter to a high degree owing to the'sudden'incrcases of the crosssection of this zoneiinmediately beneath the combustion zone "2 and in the lower part of In consequence of this loosening of the material, the passage 'of the air forced by the blower 7 through the nozzles 25 into the cooling zone 3 is very much through the nozzles '25 situated close to the kiln sole, and at'a smaller pressure'through 'the conduits 9 to the contents of the kiln. By changing the speed of the blower, the

pressure of the compressed air may be modified and by means of the needle valves providedin the nozzles 25 and the sliding members 21 the cross-sectional area of passage of the apertures connecting the'channels 20 to the conduits 9 may be adapted to the pressure of the compressed air used atthe time, so that forinstance, on the pressure being increased owing to a greater speed of the blower, an increase of the quantity of air supplied to the interior of the kiln, may be avoided by throttling the quantity of air passing into the shaft;

The result of the compressed air being introduced at'the maximum pressure close to the kiln sole, and of passages being formed through the charge in the'same, is that the compressed air can reach 'thecore of the column of the charge and assist'the combustion there. Owi'ngto the high pressure of the air at this point of introduction,a lowering of the fire by the compressed air introduced higher up,;is avoided. The airintroduced close to the sole of'the kiln, passes through the cooling zone, and thus uniformly cools the material burnt right through, while the said air, being forced to rise in "the center of' the kiln, is used forcombustion in a highly heated state, owing to which thereis a substantial economy of fuel, and the output of the'kilnis increased.

' In the gas fired shaft kiln hereinbefore deadjusted very exactly to the working conditions. 7

This avoids reduced fire and insufficient combustion or supply of air, owing to which that the result is a considerable increase of the output of the kiln with a reduced con the temperaturesinthe kilnare lowered, so 7 sumpticn of fuel. Owin to the above men tinned regulation, not en f any desired. ma

terial, whether in large or small pieces, soft or hard, wet or dry, may be treated in the kiln, but also without the least constructional change, a number of low or high grade fuels which would be out of the question Without regulation, may be used.

Asthe air is supplied to the conduits 9 through the Wall of the kiln, the'air is heatedon the way to the interior of the kiln before it mixes with the combustion gases, so that the combustion is very favorably affected. 1

By a suitable regulation of the air supply, one-sided burning is avoided. Moreover, owing to the graduation of the pressure toward the burning zone, the fire is not driven upward unnecessarily alongthe wall, as is the case, for instance, if air were to pass into the interior of the kiln through the conduits situated nearer the burning zone at the same pressure as at the bottom. In this case there takes place a very quick and intense burning along the wall, while in the interior of the kiln it lags behind, which results in irregular burning.

The discharging devices 12, 13, 14, 15 arranged beneath the outlet openings provided in the bottom of the kiln have also the effect of furthering the loosening of'the contents in the cooling zone, the constant discharge of the burnt or roasted material taking place keeping the contents of the kiln in continual motion. The automatic discharging of the contents increases considerably the output of'the kiln, as each of the dischargingdevices 12, 13, 14, 15 may be adjusted so that theamount of material discharged corresponds just to the, amount exposed to the action of the gas flames. Thus, the contents do not remain in an entirely superfluous manner for several hours in the kiln after that they have been sufliciently burnt, as it is the case in the manually discharged furnaces; on the contrary, the material of the combustion zone is slowly and continually replaced by the material sinking fromthe top toward the bottom, which results in an increased efficiency and saving of fuel.

The cross-section of the kiln can also be different from that shown, and any number of outlet openings and discharging devices may be provided. When requisite, the crosssection of the cooling zone 3 can also be suddenly increased at more than two points, while in some instances a sudden increase of said cross-section only immediately beneath the combustion zone 2 is already sufficient for obtaining the desired effect.

We claim:

1. A gas fired kiln for burning or roasting non-sintering materials, comprising a vertical shaft consisting of a pre-heating zone, a combustion zone and a cooling zone, the three zones being in vertical alinement and the cross section of the cooling zone'being suddenly increased to a considerable amount at least at one point, and means for supplying compressed air to said shaft, said means arranged to supply compressed air to the cooling zone for pro-heating by the material contained therein while on its way .to the combustion zone.

2. A gas fired shaft kiln for burning or roasting non-sintering substances, comprising. a shaft having a cross-section suddenly increasing in the cooling zone to a consider able. amount. at several points, so that the charge is suddenly loosened in said zone, means for supplying firing gases to said shaft, means for supplying compressed air to said shaft, and an eXhauster for exhaust ing the combustion gases from the shaft.

3. A gas fired shaft kiln for burning or roasting. non-sintering substances, comprising a shaft, a sourceof combustible gas arranged near said shaft, means for supplying the gases produced in said source to the shaft, a blower arranged beneath the shaft, conduits leading the compressed air from 'said blower into the interior of the shaft, and

adjustable means for controlling the pressure and consequently the quantity of compressed air supplied to the interior of the shaft by the blower and for adjusting-the cross sectional area of said conduits leading the compressed air into the interior of the shaft,

4. A gas fired shaft kiln for burning or roasting non-sintering substances, compris ing a shaft, a source of combustible gas, means for supplying the gases produced in said source to the shaft, a blower arranged beneath the shaft, conduits adapted to lead compressed air from said blower into the interior of the shaft close to its sole, further conduits adapted to lead compressed air from said blower into the combustion zone of the shaft, and adjustable means to'cohtrol the passage of the compressed air through said conduits to supply air at a maximum pressure through said first mentioned conduits and at a less pressure through said conduits discharging into the combustion zone.

5. In a gas fired shaft kiln for burning or roasting non-sintering substances, the combination with a shaft comprising a pre-heating zone, a combustion zone and a cooling zone; of a source of combustible gases arranged near said shaft, conduits arranged in the Wall of the shaft communicating with said source and adapted to supply the produced gases at the cooling zone of the shaft, means adjustable from outside the kiln for regulating the quantity of gases passing from said source .into the shaft, an air blower, conduits to lead compressed air from said blower into the interior of the shaft close to its sole, additional conduits ar= ranged in the wall of the shaft to lead compressed air-from said blower into. the combustion zone of the shaft, and means adjustable from the outside of the kiln for roasting non-sintering substances, comprising a shaft having a pre-heating zone, a

combustion zone and a cooling zone, the

cross section of said shaft increasing suddenly in the cooling zone to a considerable amount at several points,.so that the charge is suddenly loosened in-said zone, a gas generator arranged near said shaft, conduits arranged in the interior of the wall of the shaft communicating with said generator and adapted to supply the combustion gases produced in the generator: into the upper portion of the cooling zone, means adjustable from the outside of'the kiln for regulating the quantity o'f'gases passing into the shaft, a blower arranged beneath the shaft, means for. regulating the speed of" said blower, conduits for leading compressed air from' said blower into the interior of the shaft close to its sole additional conduits V for leading compressed air from said blower into the combustion zone or, the shaft, ad-

justable means adapted to control the pas sage of the compressed air through said conduits whereby the air is supplied at a maximum pressure through said first mentioned conduits 'and at a less pressure through said conduits discharging into the combustion zone, an exhauster arranged at the top of the kiln for exhausting the gases from the .pre-heating zone of the shaft, and

means for varying the, speed of the eX-" hauster.

7. A gas fired shaft kiln for burning or Copies of this patent may be obtained for five cents each, by. addressing roasting non-sintering materials, comprising a vertical shaft having a pre-heating zone,

a combustion zone and-a cooling zone of larger cross-sectional area than said combustion zone,and a second enlargement of crosssectlon at the bottom of sald coollng zone.

8. A gas fired shaft kiln for burning or roastmg non-smterlng materlals, comprising a vertical up-draft shaft having a pre-heatr ing zone, a combustionzone and a cooling.

combustion zone and a cooling zone abruptly enlarging 1n GIOSS'-S6Ct1OI1ZLl area, and means to forcibly exhaust gases from above the stock line. a

10. A gas fired shaft kiln for-burning or roasting non-sintering materials, comprising a vertical shaft containing a combustion zone and having a plurality of enlargements in cross section below said zone, whereby the lnternal cross-sectlon of the kiln 1ncreases by stages,-means for supplylng combustion gas at the bottom of the combustion zone, means for supplying air intermediate the ends of the combustion 'zone,'means for supplying air to the lower-niost zone-"of largest crosssect1on to coolithe "material in this zoneiand simultaneously heat the air as it ascends through the material to the combustion zone.

- In testlmony that we cla1m the foregoing as our invention, we have signed our names.

ARNOLD. STEIGER. WILI-IELM STEIGER- the Commissioner of Patents,

7 Washington, D. G. 

